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THE ANIMALS AND MAN 



solid particles. Now according as an injurious insect feeds 

 by one or the other of these ways, the poisonous spray or 

 insecticide must be specially chosen. For those plant at- 

 tacking insects that have chewing mouth-parts and bite 

 off and swallow bits of leaf or fruit or twig — all beetles, 

 caterpillars, slugs, locusts, etc., are of this category — some 



Fig. 90. Spraying an arsenical poison on apple trees against the codlin 

 moth. (Photograph by Dudley Moulton.) 



arsenical spray should be used. Paris green or London 

 Purple thoroughly mixed with water, ilb. to 200 gallons, 

 or a mixture of 4 ounces of arsenate of soda and 11 ounces 

 of acetate of lead in 100 gallons of water, are the best of 

 such sprays. They should be so put on as to cover the 

 attacked foliage thoroughly with a thin coating of poison. 

 Then when the beetles or caterpillars bite off and swallow 

 bits of leaf they will at the same time swallow enough poison 

 to kill themselves. 



